This invention pertains to the art of treating the by-products of metal processing, and more particularly, to the field of processing slag derived from a metal purification process involving molten metal.
As is well-known, many processes for the purification of metals involve melting a base material (such as ore, or scrap) in a furnace. The resulting liquid separates into layers according to density, generally with the desired metal at the bottom of the furnace, and with a layer of various impurities floating at the surface. Such impurities primarily consist of oxides, generally oxides of the primary metal, referred to as "slag" or "dross." Of course, processes involving mattes function in identical fashion; it should be understood that mattes are encompassed by the term "metal" as used herein.
In many instances, slag can be a valuable commercial product in its own right, as, for example, aggregate in making concrete. Processing slag to obtain the material in a usable form, however, poses problems. Traditionally, slag is tapped from the furnace and poured into a mold to cool. Of course, the molten slag is extremely hot and requires some time to cool, requiring the allocation of plant space, and when cooled, such blocks are bulky and heavy, further requiring expensive crushing and handling equipment.
One solution offered by the art to solve such problems is found in U.S. Pat. No. 3,417,930, issued to Brumagin. The apparatus disclosed there includes a tray-like conveyor, cooled by a water jacket and coupled to motors that impart vibration to the tray. Molten slag is poured onto one end of the tray, where it begins to solidify. The tray slopes slightly downward from the input end, and the vibration of the tray causes the slag to move down the conveyor. The apparatus is sized such that the slag is substantially solid by the time it reaches the end of the conveyor.
It has been found, however, that this apparatus produces slag in pieces that continue to require special handling due to their size. It would therefore be advantageous to offer an apparatus for handling molten slag that would produce small, easily processed pieces of cooled slag.